To troubleshoot a malfunctioning rear camera on your mobile device, please follow the steps below:

1. Check the settings and make sure camera has not been disabled.

2. Restart the device and see if the issue persists.

3. Check the lens for any dirt, dust, or smudges that may be causing the issue.

4. If the issue persists, make sure phone software is up to date.

5. If the issue is still persisting, seek out technical help from your device manufacturer or take it to a technician.